Trucks and SUVs traditionally provide versatility for towing and hauling. However, the power which is necessary for towing and hauling is typically provided by high-capacity engines on the trucks and SUVs. Marketing surveys have indicated that many buyers of these types of vehicles use the vehicles for towing and hauling purposes only on rare occasion, although these buyers would like to have the towing and hauling capacities of the vehicles available to them at all times. Utilizing powerful engines and reserve towing capacity, however, on vehicles usually results in a compromised fuel economy for the vehicles.
A reasonable load can be towed or hauled using a vehicle with a smaller engine, although problems can arise over the short term in particularly demanding situations. For example, pulling a boat on a trailer out of a body of water and up a boat ramp requires a high output of towing power over a short period of time. Once the trailer which carries the boat reaches level ground, the trailer can be towed using a substantially lower power output. Therefore, the capability to selectively and temporarily appropriate a large quantity of power output when necessary and then switch to a lower quantity of power output when the high power output is no longer necessary would both substantially conserve fuel and reduce emissions in the long-term.